In recent years, wireless communications have become increasingly important in a number of vehicle control systems. Remote vehicle entry transmitters/receivers, for example, are used for locking and unlocking a vehicle door, unlatching a trunk latch, or activating or deactivating an alarm system equipped on the vehicle. This remote entry device is commonly referred to a remote keyless entry (RKE) fob. The RKE fob is typically a small rectangular or oval plastic housing with a plurality of depressible buttons for activating each one of the wireless operations. The RKE fob is carried with the operator of a vehicle and can wirelessly perform these functions when within a predetermined reception range of the vehicle. The RKE fob communicates with an electronic control module within the vehicle via a RF communication signal.
More recently, complex embedded electronic systems have become common to provide access and start functions, and to provide wide ranging functions to improve driver safety and convenience. These systems include Passive Entry and Passive Start (PEPS) systems. In PEPS systems, a remote receiver and transmitter (or transceiver) is carried with the user in a portable communication device such as a key fob or a card. The portable communication device when successfully challenged transmits a radio frequency (RF) signal to a module within the vehicle for performing a variety of remote vehicle function such door lock/unlock, enabling engine start, or activating external/internal lighting. Passive entry systems include a transmitter and receiver (or transceiver) in an electronic control module disposed within the vehicle. The transceiver is typically in communication with one or more devices (e.g., door lock mechanism) for determining when a request for actuation of a device is initiated (e.g., lifting a door handle) by a user.
Upon sensing the request for actuation, the transceiver broadcasts a passive entry interrogating signal. The fob upon receiving the interrogating signal from the ECU, the portable communication device determines if the interrogating signal is valid. If it is determined a valid signal, then the fob automatically broadcasts an output signal which includes an encrypted or rolling identification code to the electronic control module. The electronic module thereafter determines the validity of the output signal and generates a signal to the device to perform an operation (e.g., the door lock mechanism to unlock the door) if the output signal is determined valid.
Although a number of vehicles functions can be controlled using wireless systems, the range of control is generally limited to one or two different range, and for RKE only. The ranges are set and typically not meant to be configurable. It is, however, desirable to vary the distance from which functions can be provided. For example, to limit draw on the battery, it is desirable to activate lights when an authorized vehicle user is in a close range. To start a vehicle in cold weather, for example, it is desirable to start the vehicle from a distance, before the authorized vehicle user leaves the house. The present disclosure addresses these and other issues.